如何在R中用FIPS代码绘制北卡县级数据交互式热力图（支持年份/变量选择）

嘿，我帮你解决这个地图需求！不管你想要只显示北卡的静态地图，还是带下拉菜单选年份、变量的交互式版本，这就给你一步步安排明白~

一、先把数据和地理文件准备好 #

首先咱们先把你的示例数据理清楚，再拿到北卡各县的地理数据，这样才能精准匹配：

# 先加载需要的包，缺一不可哦
library(tidyverse)
library(tmap)
library(sf)
library(maps)
library(maptools)
library(shiny) # 做交互式下拉菜单用

# 你的示例数据，我加了个随机种子保证结果能复现
set.seed(123)
example <- data.frame(
  fips = rep(as.numeric(c("37001", "37003", "37005", "37007", "37009", "37011", "37013", "37015", "37017", "37019")), 4),
  year = c(rep(1990, 10), rep(1991, 10), rep(1992, 10), rep(1993, 10)),
  life = sample(1:100, 40, replace=TRUE),
  income = sample(8000:1000000, 40, replace=TRUE),
  pop = sample(80000:1000000, 40, replace=TRUE)
)

# 拿北卡各县的地理数据（用sf格式更方便后续操作）
nc_counties <- sf::st_as_sf(map("county", "north carolina", plot = FALSE, fill = TRUE))

# 给地理数据加上fips编码，和你的数据匹配上
nc_fips <- county.fips %>%
  mutate(county = tolower(paste(region, subregion, sep = ","))) %>%
  filter(str_detect(county, "^north carolina,")) %>%
  select(fips, county)

# 把地理数据和你的指标数据合并到一起
nc_data <- nc_counties %>%
  mutate(county = tolower(paste(region, subregion, sep = ","))) %>%
  left_join(nc_fips, by = "county") %>%
  mutate(fips = as.numeric(fips)) %>%
  left_join(example, by = "fips")

二、静态地图方案：只显示北卡，按需选年份变量 #

1. 一次性生成所有年份+变量的分面地图 #

如果想一次性看全所有年份和变量的情况，用分面地图最直观：

# 先把数据转成长格式，方便处理多变量
nc_data_long <- nc_data %>%
  pivot_longer(cols = c(life, income, pop), names_to = "variable", values_to = "value")

# 切换到tmap的静态绘图模式
tmap_mode("plot")
tm_shape(nc_data_long) +
  tm_polygons("value", 
              palette = "viridis", # 这个配色好看还友好
              title = "指标数值") +
  tm_facets(by = c("year", "variable"), ncol = 2) + # 按年份和变量分面
  tm_layout(main.title = "北卡各县年度指标对比",
            legend.outside = TRUE)

2. 手动指定年份和变量的单张地图 #

如果只想看某一年的某个变量，比如1990年的预期寿命，这么写：

# 自己选年份和变量
selected_year <- 1990
selected_var <- "life"

tmap_mode("plot")
tm_shape(filter(nc_data, year == selected_year)) +
  tm_polygons(selected_var, 
              palette = "RdPu",
              title = str_to_title(selected_var)) + # 把变量名首字母大写，看起来更舒服
  tm_layout(main.title = paste("1990年北卡各县", str_to_title(selected_var)),
            legend.position = c("right", "bottom"))

3. 修复你之前的全美国地图问题 #

你之前的代码画了整个美国，导致北卡太小，只需要在map()函数里指定画北卡就行：

library(maps)
library(mapproj)
data(county.fips)

colors = c("#F1EEF6", "#D4B9DA", "#C994C7", "#DF65B0", "#DD1C77", "#980043")
# 先筛选1990年的life数据来演示
example_1990 <- filter(example, year == 1990)
example_1990$colorBuckets <- as.numeric(cut(example_1990$life, c(0, 20, 40, 60, 80, 90, 100)))

# 只拿北卡的县fips来匹配
nc_county_fips <- county.fips %>%
  mutate(county = tolower(paste(region, subregion, sep = ","))) %>%
  filter(str_detect(county, "^north carolina,"))

colorsmatched <- example_1990$colorBuckets[match(nc_county_fips$fips, example_1990$fips)]

# 重点！这里指定画north carolina的county，就不会画全美国了
map("county", "north carolina", col = colors[colorsmatched], fill = TRUE, resolution = 0, lty = 0, projection = "polyconic")
title("1990年北卡各县预期寿命")

三、交互式地图：下拉菜单选年份&变量 #

1. 简单交互式地图（tmap自带交互） #

如果只需要基础的点击查看详情、切换图层，直接用tmap的视图模式就行：

tmap_mode("view")
tm_shape(nc_data_long) +
  tm_polygons("value", 
              palette = "viridis",
              popup.vars = c("年份" = "year", "指标" = "variable", "数值" = "value")) + # 点击显示信息
  tm_facets(by = c("year", "variable"), sync = TRUE) # 同步缩放平移

2. 带下拉菜单的交互式地图（Shiny实现） #

如果想要明确的下拉菜单来选择年份和变量，写个简单的Shiny App就能搞定，运行后就能实时切换：

ui <- fluidPage(
  titlePanel("北卡各县交互式地图"),
  sidebarLayout(
    sidebarPanel(
      # 年份下拉菜单
      selectInput("year", "选择年份:", choices = unique(nc_data$year)),
      # 变量下拉菜单（给变量起个中文名字更直观）
      selectInput("variable", "选择指标:", choices = c("预期寿命" = "life", "收入" = "income", "人口" = "pop"))
    ),
    mainPanel(
      tmapOutput("map")
    )
  )
)

server <- function(input, output) {
  output$map <- renderTmap({
    tmap_mode("view")
    tm_shape(filter(nc_data, year == input$year)) +
      tm_polygons(input$variable, # 匹配变量名
                  palette = "RdPu",
                  popup.vars = c("县名" = "subregion", 
                                 "年份" = "year", 
                                 input$variable = input$variable)) + # 弹窗显示信息
      tm_layout(title = paste(input$year, "年北卡各县", names(input$variable)))
  })
}

# 运行App
shinyApp(ui, server)

运行这个代码后，你就能通过左侧的下拉菜单随意切换年份和变量，地图只显示北卡各县，完全符合你的需求~

内容的提问来源于stack exchange，提问作者cskn